A number of different mechanical arrangements have been employed to lock and unlock relatively slidable members. Arrangements have been developed for use with members that slide in parallel planes, and distinct arrangements have been developed for use with members that slide in a common plane, but all prior known arrangements tend to require at least two, and sometimes three, separate and distinct operations to unlatch and open one of the slidable members. That is, the prior art latching arrangements must first be unlocked, and then the members must be slid apart independently of the unlatching operation. Typically, with one prior known arrangement, one sliding member must always be opened at least a modest amount before the other sliding member can be opened at all.
One of the most successful prior latching arrangements has a keeper affixed to one sliding member, and a second, one-piece, articulating latching member affixed to the other sliding member. The latching member is comprised of three segments--viz.: a base, by which the latching member is secured to the sliding member from which it is presented; a keeper engaging latch; and, a hinge plate which is interposed between the base and the keeper engaging latch and which is connected to each by living hinges, one at each end of the hinge plate. When the base on the latching member and the separate keeper are properly affixed to the opposed slidable members, the base and keeper are coplanar and are disposed in opposition. Thus, when the sliding members are closed, the latch may be swung over the keeper, brought into mating engagement therewith and then pivoted about the keeper in an over-center locking movement accommodated by the hinge plate. This latching mechanism can be unlocked by retro-rotation of the latch. Such an arrangement is described in detail in U.S. Pat. No. 3,181,905.
The aforesaid latching mechanism operates quite well. However, in order to open the sliding members to which it is attached, the latching mechanism must first be unlatched, and thereafter the sliding member that is to be opened must be grasped and slid open. Typically, one would grasp the latch and use it as a handle to slide that member, or one would attempt to engage the keeper with a finger to slide the other member. With the sliding members closed it is sometimes inconvenient, if not impossible, to engage the keeper so that one normally opens that member to which the latch is attached, slides it a short distance and then applies a hand against the other member to open it.
Thus, even one of the most successful latching mechanisms, as disclosed in the aforesaid U.S. Pat. No. 3,181,905, requires two separate operations to open, or close, the sliding members. Moreover, a third operation may be required to open that sliding member to which the keeper is secured. In any event, this operation requires visual attention and at least modest manual dexterity, particularly if the person attempting to use the latching mechanism is normally facing away from the latching mechanism--as would be the situation when the latching mechanism is employed in conjunction with the sliding windows employed at the rear of a truck cab. It should also be noted that living hinges have a limited life so that it is generally necessary to replace the prior art latching member from time to time.